Recently, an LED which emits white light has been fabricated to include a Ga(In)N light emitting diode which emits blue light at about 460 nm and a YAG:Ce3+ phosphor which emits yellow light (BY emission method, U.S. Pat. No. 5,998,925 and EP 862794). However, the LED for use in emission of white light is limitedly used, since it has a low color temperature of about 6,000 to 8,000 K and a low color rendering index of about 60-70 due to the absence of a predetermined color component (e.g., red).
Alternatively, white color is realized by mixing three red, green and blue colors (RGB emission method), which is disclosed in detail in WO 98/39805.
However, since the RGB light emitting diodes have different constitutive materials or properties to one another, their luminous intensities vary. Accordingly, it is impossible to actually reproduce all colors in a visible light wavelength range using the RGB emission method.
That is, red light, green light and blue light are sequentially shortened in wavelengths, and thus, the light emitting diodes have low luminous intensities due to the short wavelengths. As such, the red and green light emitting diodes have relatively higher luminous intensities than the blue light emitting diode. In recent years, the difference in relative luminous intensities of the light emitting diodes has further increased due to the techniques for fabricating LEDs. Consequently, white light for use in desired purposes, for example, lighting fixtures or automobiles, cannot be realized even by the RGB emission method using three RGB light emitting diodes having different wavelengths.